Transmission



March 6, 1951 P, H, PALEN ETAL 2,544,542

March 6, 1951 P. H. PALEN E1YAL 2,544,542

TRANSMISSION Filed Set. '7, 1945 4 Sheets-Sheet 2 ATT RNEY March 6, 1951 Filed Sept. 7, 1945 P. H. PALEN ETAL TRANSMISSION 4 Sheets-Sheet 4 PETER H. PALEN.

ATTURNEY INVE ORS w.Bu ETT.

UNITED STATES PATENT OFFICE TRANSMISSION Peter H. Palen, Paterson, and Harry W. Burdett,

Glen Rock, N. J., assignors to Wright Aeronautical Corporation, a. corporation of New York Application September 7, 1945, Serial No. 814,850

' 4 Claims. (Cl. 'i4- 688) 'I'his invention relates `to' multi-speed transmissions and is particularly directed to a transmission aiiording four speed ratios. The invention is described in connection with a multi-speed drive from an engine to a supercharger therefor.

However, the inventionis not limited to this specif'lc application'but instead is of general utility.

It is an object of this invention to provide av novel four-speed transmission in which the load is divided between two parallel paths in all but one of the speed ratios. The transmission includes two friction brakes and a hydraulic coupling and .the arrangement is such that two of the speed ratios are effected with both friction brakes disengaged by emptying and filling the hydraulic coupling. The other two speed ratios are effected with thecoupling full by engaging one or the other of the friction clutches.

With the present invention, wear and scuffng of the friction brakes is minimized because the brakes are arranged to engage substantially without shook and under only small loads. To this end, the hydraulic coupling not only acts as a shock absorber during engagement and disengagement Y l of the friction brakes, but the hydraulic coupling also is controlled to unload the drive including .the friction-brakes prior to their engagement or disengagement. In4 addition,`the hydraulic coupling acts to dampen torsional vibrations while vat least a portion of the load is being transmitted through the coupling.

It is a further object of this invention to provide a novel means for controllingv the slip of the hydraulic coupling. Specifically, the vaned hydraulic coupling elements are adapted to be moved axially relative to each other to control the slip of the coupling.v In addition, it is an object of this invention to provide novel means for frictionally lockingr the coupling elements together when the coupling elements are in position for minimum slip.

Other objects of this invention will become apparent upon reading the annexed detailed description in connection with the drawing in which:

Figure 1 is an axial sectional view through a transmission embodying the invention; K

Figures 2, 3, 4 and 5 are sectional views taken along lines 2-2, 3 3, 4-4 and 5-5 of Figure 1;

Figure 6 is a sectional view of a fluid pressure control valve for use with the transmission of Figure l;

Figure 7 is a sectional View taken along line 1-1 of Figure 6; and

secured to bolts 22 passing through the studs I6.

Each double planet pinion I8 comprises a pair of integrally formed pinions 24 and 26 disposed in meshing engagement with annular gears 28 and 30 respectively. The gear 28 is formed on the output shaft 32 which is adapted to drive a supercharger (not shown) while the gear 3U acts as a torque reaction member for the drive through the double planet pinions I8. Reaction gear 3D has a rim portion 34 piloted on a drum 36 secured to the fixed housing structure 3B by bolts 4U. Oneway or over-running brake rollers 42 are disposed between the reaction gear rim 34 and the drum 36. The reaction gear lrim 34 is provided with a plurality of conventional one-way brake cam surfaces 44 providing wedge-shaped spaces within which the rollers 42 are disposed.

With the shaft I0 rotating clockwise, as viewed in Figure.2, the reaction gear 30 also tends to rotate clockwise and the orientation of the cam surfaces 44 is such that clockwise rotation of the reaction gear 30 is prevented by wedging of the rollers 42 between the cam surfaces 44 and the drum 36.

The aforedescribed planetary gear train provides a step-up speed ratio from the input or engine shaft I0 to the supercharger or output shaft 32. A further step-up in the speed ratio may be effected by rotation of the reaction gear 30 counterclockwise, as viewed in Figure 2, that is, in a direction opposite to the reaction torque acting thereon as a result of the drive through the double planet pinions I8. With this construction, it is possible to provide a plurality of differbetween the coupling runner or element 54 and an internal annular ange 62 adjacent the outer y plementary vaned coupling element 64 through the hydraulic liquid within the working chamber 65 disposed between the coupling elements 54 and 64. The driven coupling element 64 is splined at 66 to a planet carrier member 68 having a. plurality of studs 10 projecting therefrom. A simple planet pinion 12 and a compound or double planet pinion 14 are journaled about each stud 10 and are held thereon by machine screws 16.

The planet pinions 'l2 are disposed between and in meshing engagement with concentric annular gears 18 and 80. The gear 18 is adapted to be frictionally held against rotation by engagement of a brake 82. The double planet pinions 14 each comprise integrally formed pinion gears 84 and 86 of which the gears 04 engage an outer annular gear 88. The rim of the gear 88. also forms the cam member of a oneway or over-running brake comprising 'rollers and a drum member 92 splined to the member 94 which, in turn, is flxedly secured tothe housing 38. As illustrated in Figure 4, the rim of the annular gear 88 is provided with cam surfaces 96 so oriented that, with clockwise rotation of the planet carrier 68, clockwise rotation of the gear 88 is prevented but the gear 88 is free to rotate in a counterclockwise direction.

The gear 86 of each double planet pinion 14 is disposed between the outer annular gear 98 and the inner annular gear |00. The outer annular gear 98 is adapted to b e frictionally held against rotation upon engagement of a brake 02. The hub I0| of the inner annular gear |00 is connected to the hub |04 of the gear 80 through a one-way or over-running clutch comprising rollers |06 and cam surfaces |08 on the hub |04. The orientation of the cam surfaces |08 is such that, as illustrated in Figure 3, the one-way clutch |06 permits the gear 80 to overrun the gear 14.

The hub |04 of the gear 80 is splined at |09 to the annular gear ||0 which, in turn, meshes with gears ||2 of a plurality of double pinion gears ||4. The other gear ||6 of each of the double pinion gears ||4 is disposed in meshing engagement with a second gear ||8 formed on the rim 34 of the reaction gear 30. The double pinions ||4 are journaled about fixed studs |20 formed on an annular member |22 which, in turn, is piloted about the hub of the planet carrier I4. The member |22 is held against rotation by a plate |24 secured thereto and splined at |26 to the fixed drum 36. With this construction, the gear ||0 is adapted to drive the gear ||8 and consequentbl the reaction gear 30 in a direction opposite to the reaction torque acting on the gear 30 from the pinions 26. 'I'hat is the gear 30 is driven in a counterclockwise direction (as viewed in Figure 2), this direction being opposite to the direction of rotation of the gear ||0.

|36 relative to which the piston |32 is slidable. The arrangement is such that, when fluid under pressure is supplied to the chamber |36 through a passage |38 and conduit |40 from a valve |4| hereinafter described, the plates |28 and |30 are frictionally clamped together to lock the gear 18 against rotation. 1

The brake |02 may be similar to the aforedescribed brake 82 and, as illustrated. comprises a plurality of alternate frictionally engageable plates |42 and |44 respectively splined to the rim of the gear 98 and to the annular member 94 secured to the housing 38. A piston |46 is provided with seal rings |48 cooperating with the member 94 to provide a sealed annular chamber |50 relative to which the piston |46 is slidable. Fluid under pressure is adapted to be supplied to the chamber |50 through a passage As illustrated, the brake 82`comprises avplurality of alternate frictionally engageable plates |28 and |30 respectively splined to the rim of the gear 18 and to the annular member 92 secured to the housing 38. A piston |32 is provided with seal rings |34 cooperating with the member 92 to provide a sealed annular chamber |52 and conduit |54 under the control of the valve |4| to frictionally clamp together the plates |42 and |44 thereby locking the gear 98 against rotation.

In brief, the input shaft I0 is drivably connected to the output shaft 32 through the planet pinion carrier I4, the gear 30 providing the reaction torque for power transmitted through said carrier. In addition, the input shaft l0 is drivably connected to the reaction gear 30 for driving said gear in a direction opposite to said reaction torque. The last-mentioned driving connection includes the hydraulic coupling 56 and a variable speed ratio gear set connected in series with said coupling between the input shaft I0 and said gear 30. This variable speed ratio gear set comprises the pinions 12, 14 and ||4, the gears meshing with said pinions and the associated clutches and brakes.

With the aforedescribed construction, first or low speed is provided with the hydraulic coupling 56 unloaded. In this condition of the transmission, power is transmitted from the input shaft I 0 through the planet pinion carrier I4 and its double planet pinions I8 to the output shaft 32, thereby providing a step-up speed drive ratio from the input shaft |0 to the output shaft 32. The roller brake 42 prevents rotation of the reaction gear 30 in the direction of the reaction torque acting upon the gear 30that is clockwise as viewed in Figure Z-with a clockwise rotation of the shaft I0. Also, since the hydraulic coupling 56 is empty in first speed, no power is transmitted through any of the other gears of the transmission and therefore the reaction gear 30 remains stationary in first speed.

In second, third and fourth speeds. power is transmitted from the input shaft |0 to the output shaft 32 through the planet Pinion carrier I4 and its double planet pinions 8, as in first speed. In addition, power is transmitted through the hydraulic coupling 56 to drive the reaction gear 30 counterclockwise as viewed in Figure 2. That is, the gear 30 is driven in a direction opposite to the direction of the reaction torque acting thereon resulting from the power transmitted through the planet carrier |4, thereby lproviding a step-up in the Speed drive ratio above the rst speed ratio by an amount depending on the speed at which the reaction gear 30 is thus driven.

In the second speed, the hydraulic coupling 56 is filled and both friction brakes 02 and |02 are disengaged. The reaction gear 30 is then driven from the shaft I0 through the hydraulic coupling 56. planet carrier 68, double planet pinions 14, one-way clutch |08, gear and double pinions |-l4 to the reaction gear 30. In this secauana ond speed, the reaction torque necessary for driving the gear 30 is provided by the roller brake 90 which prevents rotation of the annular driving the gear 30. The gear 30 is driven from the input shaft I0 through the' hydraulic coupling 56, planet carrier 68, planet pinion gears 86, annular gear |00, one-way clutch |06,.gear ||0 and the double pinions H4. In this condition of the transmission, the roller .brake 90 through the hydraulic coupling 56, planet carrier 68, planet pinion gears 12, gears 80 and ||0 and the double pinion gears ||4. In this condition of transmision, the brake 82 provides the' necessary reaction torque to drive the gear 30 while the roller brake 90 and roller clutch |06 over-run. Friction brake |02 preferably remains engaged in -fourth speed, but this brake has no operating effect in fourth speed since the gear 80 is driven at a speed greater than that of the gear |00 so the clutch |06 over-runs.

If desired, the friction brake |02 could be disengaged in fourthspeed, in which case the oneway clutch |06 would not be necessary. Also it should be obvious that other conventional types of clutches and brakes could be substituted for various clutches and/or brakes illustrated.

summarizing, in first speed the hydraulic coupling is unloaded and both friction brakes 02 and |02 are disengaged. In second speed, the hydraulic coupling is loaded and both friction brakes are still disengaged. In third speed, the

`tion gear y30 is driven from the input shaft |0 hydraulic coupling is loaded and the frictionv brake |02 is engaged. In fourthspeed, both friction brakes are engaged and the hydraulic coupling is loaded, although in this speed, only friction brake 82 has any operating effect. When the speed of the output shaft is reduced to any lower ratio, the above sequence is merely reversed.

As hereinafter described the hydraulic coupling 56 is unloaded between second, third and fourth speeds. However there is no power off interval during shifts between these speeds because the planet carrier |4 continuously transmits power.

The hydraulic coupling 56 comprises the conventional vaned coupling elements 54 and 64 vbetween which the working liquid of the coupling is adapted to be disposed in the chamber 65. Liquid is supplied to the coupling working chamber 65 from the valve |4| through conduit |60, passages |62 and |64, annular space |66 and passage |68, the ends of the annular space |66 Ibeing closed by the seal rings 58. Fluid under Figure 1 to reduce the clearance'between the coul pling elements-64 and 84. The seal ring 60 is adapted'to partially uncover one or more slots |16 in the flange 62 after the coupling element 54 has thus moved to the left to a predetermined position close to the other coupling element 64.

The arrangement is such that when fluid under pressure is'supplled to the coupling chamber 63, the coupling element 54 moves toward its complementary element 64 until the fluid pressure leakage through the slots |16 and thence through the openings |18 in the rim of the member 50 is such magnitude that the pressure within the chamber 63 balances the opposing pressure of the` fluid withinthe hydraulic coupling chamber 65. The one or more slots |18 are so-disposed that, when thepressure on opposite sides of the coupling element 54 is balanced, there is only a small clearance between the coupling elements 54 and 64 whereby the coupling operates with a minimum of slip. When the fluid pressure to the coupling chamber 63 is cut off, the coupling elements 54 and 64 separate, whereupon the slip between these elements greatly increases thereby at least partially unloading the coupling.

In order to further increase coupling slip when the fluid pressure is cut off from the chamber 63, the rim of the annular member 50 is provided with one or more slots |80. The slots |80 are disposed s0 that, when pressure is applied to the chamber 63 and the coupling elements have moved close together as illustrated in Figure 1, the rim of the member 50 substantially seals the annular clearance |82 between the outer periphery of the coupling elements 54 and 64. But, when the chamber 63 is cut off from the source of fluid pressure, the coupling elements 54 and 64 separate and uncover the slots |80. Leakage of the coupling kliquid from the chamber 65 through the slots |80 increases the slip of the coupling and also helps to remove the heat produced within the coupling because of this slippage. The coupling is also provided with a drain opening or openings |83 adjacent its hub to provide a continual but'l small circulation of fluid through the coupling working chamber 65.

The supply of iluid pressure to the hydraulic coupling 56 is coordinated by the valve |4| with the supply of fluid pressure to the friction brakes 82 and |92 in such a manner that the pressure supplied to the coupling chamber 63 is cut off before engagement or disengagement of the brakes I82 or |02. In this way, thedrive to the reaction gear 30 is relieved of load `prior to engagement or disengagement of the brakes 82 and |02 thereby minimizing the Wear caused by slippage between their friction plates.

Figure 6 illustrates a suitable valve |4| for controling the supply of fluid pressure to the coupling 56 and to the friction brakes 82 and |62. As illustrated, the valve comprises a body portion |84 having a bore |86 for the reception of plugtype valve member |88. The valve member |88 has a flat |90 formed on one side and terminating short of the ends of this member. In addition,

third radial hole 206 extends outwardly from the pasage |98 and is spaced from the annular groove |86 by an amount equal to the spacing of the annular grooves about the valve member.

'I'he valve member |88 is designed to be moved to any one of four positions-one for each speed ratio of the transmission-by an arm 208 extending therefrom. A set screw 2I0 is adapted to prevent rotation of the valve member |08. As illustrated in Figure 6, the valve member |88 is in its first speed position and, as indicated in this ligure, it may be moved to the right to its second, third and fourth speed positions. The first, second, third and fourth speed-ratio positions of the arm 208 are indicated on Figure 6 by the reference letters A, B, C and D respectively, the space between adjacent speed-ratio positions being equal to the space between adjacent grooves |92, |94 and |96.

Liquid under pressure-for example, engine lubricating oil-is supplied to a conduitl 2 I2 which extends through the valve body |84 and opens into the flat |90 on the valve member I 88. In addition, a conduit 2| 4, connected to a suitable drain, extends through the valve body and opens into the bore |86 therein. Accordingly, since the valve member passage |98 extends between the ends of the valve member, the opposed ends of the valve bore |86 are connected to the drain conduit 2I4. The conduits |40, |54, |60 and |10 also open into the bore |86 of the valve body at a spacing corresponding to the spacing of the valve member |88 between its various speed ratio positions. In addition, conduits I 40, I 54 and |60 are disposed in a common plane with the flat |90 and the conduit 2I2 and the conduit |10 is disposed in a common plane with the passages 200 and 202.

A pressure-reducing valve 2I6, urged in a closing direction by a spring 2I8, is disposed in the conduit |60. When liquid is supplied through the conduit |60 to the working chamber 65 of the hydraulic coupling, there is a continual small circulation of liquid through the coupling as provided by tlie openings |83 so that the valve 2|6 is effective to reduce the pressure of the liquid supplied to the coupling chamber 65.

The construction of the valve |4I is such that, in the rst speed position, the working chamber 85 and the pressure chamber 63 of the hydraulic coupling and both friction brakes 82 and |02 are vented or drained to the conduit 2I4. Accordingly, in rst speed, there is no drive to the reaction gear 30 through the hydraulic coupling 56 and the entire drive of the output shaft 32 is through the double planet pinions I8. In the second speed position of the valve member |88, the annular groove |96 is alined with the conduit |10 and the conduit 2 I 2 is in communication with the conduit |60 through the fiat |90. Accordingly, liquid under pressure is now supplied to the working chamber 65 of the coupling through conduit |60 and to the coupling pressure chamber 63 through the conduit |10. However, conduits |40 and |54 are still connected to the drain passage 2 I4 so that both friction brakes remain disengaged. Accordingly, in second speed the hydraulic coupling 56 is loaded but both friction` to the reaction gear 30. Upon completion of this shift to third speed. the source of fluid pressure in the conduit 2I2 is connected to the conduit |54 via the fiat to effect engagement of the brake |02. At the same time, the annular groove I 84 is alined with the conduit |10 to restore the pressure in the coupling pressure chamber 33 thereby reloading the coupling and restoring the drive to the reaction gear 30. The reloading of the coupling 56 takes longer than the engagement of the brake |02 so that, upon shift to third speed from second speed, the friction brake |02 is engaged while the hydraulic coupling is momentarily at least partially unloaded by the separation of the coupling elements 54 and 64. That is, the friction brake |02 is engaged under substantially no load.

During the shift to third speed, as well as during the shift to fourth speed, liquid is continually supplied to the coupling working chamber 65 via the fiat and conduit |60. It should also be noted that, when the pressure to chamber 63 is cut off and the coupling elements 54 and 64 separate, the coupling drain port |80 is opened and the resulting flow of liquid therethrough from the coupling chamber 65 is effective to remove the heat generated by the coupling slip.

As the valve member |88 is moved to its fourth speed position, the drain passage 200 is momentarily alined with the conduit |10 thereby venting or draining the coupling pressure chamber 63 just as in the shift from second speed to third speed. As a result, the coupling 56 is momentarily at least partially unloaded and upon completion of the shift to fourth speed, the flat |90 establishes communication between the source of pressure in conduit 2| 2 and the conduit |40 to effect engagement of the friction brake 82. At the same time, the annular groove |92 is alined with the conduit |10 to restore the pressure in the coupling chamber 63 and again load the coupling and restore the drive to the reaction gear 30. It should also be noted that in the shift from third to fourth speed, the conduit |54 remains connected to the source of fluid pressure in the conduit 2I2. Accordingly, friction brake |02 remains engaged in fourth speed but, as previously noted, this has no operating effect.

When the valve member |00 is moved in a down shift direction, this above sequence is reversed and the friction brakes 02 and |02 are at least partially unloaded prior to their disengagement by cutting on' the pressure to the coupling chamber 63 to at least partially unload the coupling.

With the aforedescribed construction, the friction brakes 82 and |02 are engaged and disengaged while under substantially no load thereby minimizing wear and scuilng of their brake plates. In addition, these brakes operate under a relatively small load because they only control the drive from the input shaft I0 through the reaction gear 30 to the output shaft 32, which drive, in effect is in parallel with the drive through the planet pinion carrier I4 to the output shaft 32. Because of this parallel drive arrangement, the hydraulic coupling also does not carry the full load.

The conventional hydraulic coupling, when full of liquid, operates with a small amount of slip. Figures 8 and 9 illustrate a modification in which the coupling elements are vfrictionally engaged to to prevent any slip of the coupling.

In Figures 8 and 9, an annular drive member 220 is splined at 222 to a varied element 224 of a hydraulic coupling 226 and a complementary 9 vaned element 228 is adapted to be driven thereby. The working chamber 280 of the hydraulic coupling between the coupling elements 226 and 228 is supplied with liquid through a psage 282, annulus 234 and the passage 236, the ends of the annulus 234 being closed by seal rings 268. A seal ring 240 is disposed between the coupling element 224 and the annular drive member 220 adjacent the outer periphery of these members and the seal ring 248 together with one of the "/seal rings 238 defines a sealed annular chamber 242. The chamber 242 is supplied with a liquid or fluid ypressure through a passage 244.

The vaned coupling elements 224 and 228 are provided with facing conical frictionally engageable annular members 244 and 246 adjacent their outer peripherythereby providing a friction cone clutch. When the chamber 242 is subjected to a suitable pressure, the coupling element 224 moves toward the coupling element 228 until the cone clutch members 244 and 246 engage as illustrated in Figure 8. The supply of liquid to the coupling chambers 280 and 242 may be similar to that illustrated in Figure 1 in connection with the hydraulic coupling 56.

With this construction, when the pressure is cut off from the chamber 242, the liquid pressure within the coupling chamber 230 causes the coupling element 224 to move away from the coupling element 228as illustrated in Figure 9,

whereupon the coupling operates with a maximum of slip. Upon the application of pressure to the coupling chamber 242, the coupling ele ment 224 moves toward the coupling element 228 thereby reducing slip of the coupling. The cone clutch members 244 and 246 are disposed to engage just as the coupling elements 224 and 228 approach a position of minimum slip. In this way, the cone clutch members are brought to very little relative slip prior to their engagement. In addition, prior to engagement of the cone clutch members 244 and 246, there is continuous leakage of liquid radially outwardly through the clearance 248 between the vaned coupling elements 224 and 228. This escaping liquid flows over the surfaces of the cone clutch members 244 and 246 thereby helping to remove the heat produced by their relative slippage as these members engage. Engagement of the cone clutch members 244 and 246 is effective to shut off this fiow of the coupling liquid radially outwardly through the annular clearance 248.

In Figures 8 and 9, there is no drain opening at the outer periphery of the coupling chamber 242 corresponding to drain opening or slots |16 of vFigure 1, since in Figures 8 and 9 engagement of the cone clutch members 244 and 246 limits movement of the coupling elements 224 and 228 toward each other. Also the friction engaging surfaces 244 and 246, instead of being conical. obviously could be fiat.

While we have described our invention in detail in its present preferred embodiment, it will be obvious to those skilled in the art, after understanding our invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. We aim in the appended claims to cover all such modifications.

We claim as our invention:

l. A multi-speed transmission comprising an input shaft; an output shaft; means providing a driving connection between said shafts; said means including a member subjected to reaction torque resulting from the transmission of torque by said means from said input shaft to said output shaft; means operable to prevent rotation of said reaction member at least in the direction of said reaction torque to provide a speed ratio drive from said input shaft to said output shaft; means operable to drivably connect said inputI shaft to said reaction member for driving said member from said input shaft in a direction opposite to said reaction torque at any one of a plurality of speed ratios thereby providing additional speed ratio drives between said shafts; said last named means including a hydraulic coupling and a variable speed ratio gear set connected between said input shaft and said torque reaction member; and means for changing the speed ratio of said gear set-and for controlling said hydraulic coupling so as to at least partially unload said coupling during a speed ratio change of said gear set.

2. A multi-speed transmission comprising an input shaft; an output shaft; means providing a driving connection between said shafts; said means including a member subjected to reaction torque resulting from the transmission of torque by said means-from said input shaft to said output shaft; means operable to prevent rotation of said reaction member at least in the direction of said reaction torque to provide a speed ratio drive from said input shaft to said output shaft; means operable to drivably connect said input shaft to said reaction member for driving said reaction member from said input shaft in a direction opposite to said reaction torque at any one of a plurality of speed ratios thereby providing additional speed ratio drives between said shafts; said last named means including a hydraulic coupling and a variable speed ratio gear set serially connected between said input shaft and said torque reaction member; and means for at least partially unloading said hydraulic coupling when changing the speed ratio of said gear set.

3. A multi-speed transmission comprising an input shaft; an output shaft; means providing a driving connection between said shafts; said means including a member subjected to reaction torque resulting from the transmission of torque by said means from said input shaft to said output shaft; means operable to prevent rotation of said reaction member at least in the direction of said reaction torque to provide a speed ratio drive from said input shaft to said output shaft; means operable to drivably connect said input shaft to said reaction member for driving said reaction member from said input shaft in a direction opposite to said reaction torque at any one of a plurality of speed ratios thereby providing additional speed ratio drives between said shafts; said last named means including a hydraulic coupling and a variable speed ratio gear set serially connected between said input shaft and said torque reaction member; and means for changing the speed ratio of said gear set and for at least partially unloading said hydraulic coupling during a speed ratio change of said gear set.

4. A multi-speed transmission comprising an input shaft; an output shaft; a planetary gear train providing a driving connection between said shafts; said planetary gear train including a member subjected to the reaction torque resulting from the transmission of torque by said gear train from said input shaft to said output shaft; means operable to prevent rotation of Said reaction member at least in the direction of said reaction torque to provide a speed ratio drive from said input shaft to said output shaft; means operable to drivably connect said input shaft to said reaction member for driving said reaction torque at any one of a plurality of speed ratios thereby providing additional speed ratio drives between said shafts; said last named means including a hydraulic coupling and a variable speed ratio gear set serially connected between said input shaft and said torque reaction member; and means for changing the speed ratio of said gear set and for at least partially unloading said hydraulic coupling during a speed ratio change of said gear set.

PETER H. PAIEN. HARRY W. BURDE'IT.

l2 REFERENCES crrnn The following references are of record in the file of this patent: I

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